1. Field of the Invention
The invention relates to connection devices and, more particularly, to a connecting apparatus for interconnecting field devices, comprising a bus connection for connection to a bus and a field device connection for connection of a field device.
2. Description of the Related Art
WO 2005/053221 A2 discloses connecting apparatuses. Reference is expressly made to WO 2005/053221 A2 with regard to the capability to implement the present invention with respect to the connecting apparatus for field devices during operation of a network, such as a Profibus PA network. Accordingly, the content of WO 2005/053221 A2 is incorporated herein by reference in its entirety.
In the case of connecting apparatuses for field devices that communicate over a bus, i.e., a fieldbus, with a superordinate automation appliance, the bus cable forms a common component for all the field devices. Consequently, the failure of the bus cable affects all the field devices. Furthermore, faults in the field devices, such as a short on the transmission line or emission of disturbance signals on the transmission line, can adversely affect the communication of the other field devices connected to the fieldbus.
An extension of a fieldbus with field devices, such as a Profibus PA/Foundation Fieldbus (PA/FF), should be possible during operation without disturbing the fieldbus or its subscribers that are connected to the fieldbus. When field devices are being connected to the connecting apparatus, the communication of all the appliances or other field devices can be disturbed by a current change on the fieldbus.